Electric furnace.



I J. THOMSON.

ELECTRIC FUBNAGE.

APPLIOATION FILED SEPT. 1. 1909. 90,881 I Patented Mar. 1, 1910. I

WITNESSES IIVI/ENTOR AITORNEYS UNETED @l ldn ildh aj @lilFIGE JOHN THOMSON, OF NEW YORK, N, Y., ASSIGNOR T IMBERT PROCESS COMPANY,' OF

NEW YORK, N. Y., A CORPORATION 01 NEW 'YOBK.

. u may be formed.

The resister is compounded intwo secearnest.

ELECTRIC FURNACE.

To all whom it may concern:

3e it known that I, Jonn THOMSON, a citizen of the United States, and a resident of the borough of Manhattan of the city of New York, in the county and State of New York, have invented certain new and useful Improvements in Electric Furnaces, of which the following is a specification, reference being had to the accompanying drawings, forming a part hereof.

The invent-ion relates more particularly to improvements in resisters of electric furnaces and to the parts immediately asso ciated therewith, and one of its objects is to provide a resistor, composed of a plurality of members, which may be supported or suspended at its ends upon the furnace walls, but which shall otherwise be self supporting while spanning the chamber in a direct line.

In another application for Letters Patent filed September 1, 1909, Serial No. 515,698 I have shown how a resister, composed of a plurality of elements, may be supported wholly from its ends through the interlocking of its elements. In the present case, the

resistor elements are not interlocked with each other nor with the terminals but, in accordance with the invention, are composed of irregular or wedge-blocks arranged to form what is known architecturally as a flat arch. V

Another object of the invention is to form the resister or elements thereof so that it shall have a high resistivity and also to provide means for automatically compensating variations in its length due to thermal changes, without materially increasing or decreasing the initial compression therein.-

Referring to the drawings, Figures 1 and 2 are respectively a longitudinal center section and a transverse center section through an electric furnace embodying the improvements, and," Fig. 3 is a perspective .View,

I partly broken away, showing two adjacent blocks and the grooves formed in their abutting faces.

In said furnace the melting chamber 0 is suitably formed in the brick-work c, being provided with a refractory lining c and a cover Z) through which a charging opening Specification of Letters Patent.

Application filed September 1, 1909.

Patented Mar. 1, 1910. Serial no. 515,701.

tions, denoted generally by D and D, and these sections are shown as being'connected up in parallel. between the terminals 6 and c. In the drawings, the heat waves passing to the charge are represented by arrows, the arrows on representing the direct waves and the arrows 2 the indirect waves. Each section of the resister is constructed, in the present case, of irregular or wedge-blocks d whose sides generally converge to a common center but are formed to produce a beam whose upper and lower surfaces are parallel each to the other, thus constituting what is designated architecturally as a flat arch. The controlling advantages of this form of arch over that where the upper and "lower surfaces are arcs of circles, are that the exend blocks. Now, it will be understood that when the resister becomes highly heated the blocks will expand thus requiring some means to be provided, in cases where they are closely compacted, as here, for preventing deformation thereof and for preserving so far as possible the initial compression therebetween. For this purpose, the ends of the resistor sections are beveled and the brick-work facing the ends of the resister sections is beveled in the opposite direction, as shown clearly in Fig. 1 of the drawin s, and wedge-shaped connecting or con ucti pieces are inserted between the brick-wor and the ends of the resistor sections. In the present case, these pieces are formed integral with the terminals 6 and e respectively and thus may be referred to as the terminals. Assuming new that the angle on each side of each connector piece or terminal is approximately equal to that of the wedge-blocks, then the sum of the two is double and for a given end-thrust along the line 1', the said connectortpiece or rise over that of any 'of the resists: memterminal will have twice the tendency to I hers. The consequence is that the terminals, being freely mounted in the cover, will rise or fall as the resister expands or contracts, whereby a practically uniform state of contact resistance can be automatically maintained. And it will be obvious that the Wed e connector pieces or terminals may be emp oyed in other ticularly Where the resistor elements are closely compacted, as in the present case, with the same utility and eti'ect. Where the lower ranges of electrical resistance are desired,-the wedge-blocks should have smooth surfacesat their contactin faces, but Where igher resistances are to %e obtained, as is usual in modern practice, these faces may be formed so that only a portion of one face will contact with its opposin face. For, longitudinal recesses (Z may e formed in one of the faces or each block so that, when the blocks are laced together With the faces containing the ongitudinal recesses abutting against smooth faces, as illustrated in Fig. 1, then the raised portions formed by the longitudinal recesses in any face will alone contact .with the opposing smooth face and will form line contacts, as is obvious. Again, by forming transverse grooves, as 03 whose raised portions may contact against a smooth surface, the same result is accomplished as in the case of the longitudinal grooves. Finally, by combining longitudinal recesses in one surface and transverse recesses in an abuttin'g surface, the recesses in such opposing surfaces lying at right angles to each other as indicated In Fig. 2, there will result a oint or lot contact between opposing b ocks. Thus, Where line contacts are employed a comparatively high resistance may be ob tained, and where point and dot contact are used, a still higher resistance will result.v It is to be noted, particularly in View of the application for Letters Patent alluded to hereinbefore, that in the instances here cited there is no interlocking of the recesses nor do they act in any Way to sustain or assist in sustaining the resister as a whole. Moreover, the recesses have a contingent advan tage in that they afiord, especially when the grooves are crossed upon each other, an excellent and rapid escape for the heat developed in the interior of the resister.

It, Will be obvious that the terminals may be otherwise located than in the cover and movin vertically, the connector pieces at the en s of the resistor sec.

that, instead of tions may move along the line 1 against any adequate mediumoi resilient or manual adjustment (not shown) Without departing from the spirit of the invertion.

I claim as my invention: 1. An electric furnace having a eels-sup porting resister composed of a plurality forms of resisters par irregular blocks arrau g ci'l in the form of a flat are 1.

2. An electric furnacehaving a self-supporting resistor composed of a plurality oi irregular carbon blocks shaped so as to form when assembled a flat arch.

3. An electric furnace having a rcsisier composed of a plurality of elements and Wedge shaped conducting piece. at each end of the resistor, said pieces being movable to compensate for thermal changes.

4-.An electric furnace having a resistor composed of a plurality of members and supported from the end members Wedge shaped conducting pieces abutting against said end members respectively, said pieces being movable to compensate for thermal changes.

5. An electric furnace having a self-supporting rcsister composed of a plurality oi": irregular blocks arranged to form a flat arch, and means for :mtomatically compensating variations in the length of the resister due to thermal changes.

6. In an electric furnace, a. resister composed of Wedge shaped carbon blocks arranged in a direct line and supported Wholly from the end block 7. In an electric furnace, a flat resister formed of Wedge-blocks, the said resister spanning the melting chaznher and being supported Wholly by the brick-Work at each end and terminal connections for said re ister.

8. in an electric furnace, a Hat ister formed of wedge-blocks, the said resister spanning the melting chamber and being supported by the brick-Work, and beveled conducting pieces at the ends of the resister against which the resister in'ipinges right and left, the said conducting pieces being adapted to yield to compensate variations in the length of the resister due to thermal changes. I

9. In an electric furnace, a flat resister composed of wedgebloclts. and Wedge-terminals interposed at each end between the resistor and the brick-Work.

10. An electric furnace having a com.- pound resister each section of which is composed of Wedge-blocks arranged in a direct line, and Wedge terminals at each end connecting said sections in parallel and adapted to compensate variations in the lengthof said sections due to thermal changes.

1". In electric furnace, a resister formed of aplurality of members, some of the members havin oue surfaee grooved reduce the area 01' contact between such members and adjacen members.

In an electric furnace, resiste blocks, some of the having one son grooved to reduce a of contact between such blocks a blocks.

thereof, and i gamer I e 13. In an electric furnace,' a resister com- -faces' are grooved crosswise to each other in 10 posed of a plurality of members having order to produce oint contacts at or near grooved surfaces, the blocks being arranged the intersections of said grooves. so' that the grooves run crosswise to each This specification signed and witnessed 5 other in opposing faces of adjacent blocks this 31st day of August, A. 1)., 1909. i

in order to produce point contacts between JOHN THOMSON. the blocks. Signed in the presence of 14. In an electric furnace, a resister com-. M. RoLLINe,

posed of wedge-blocks whose contacting sur- G. MCGRANN. 

